PPG authentication method and device

ABSTRACT

A photoplethysmogram (PPG) authentication method and device, where it is detected whether a terminal currently meets a PPG signal pre-collection trigger condition, and collection of a current PPG signal of a user is triggered only when the PPG signal pre-collection trigger condition is met such that the PPG signal of the user is pre-obtained before an application requests PPG authentication. In this way, when it is detected that the application initiates a PPG authentication request, PPG authentication may be directly performed based on a most recently collected PPG signal, thereby ensuring timeliness of PPG authentication, avoiding resource consumption caused by periodic PPG signal collection, and reducing power consumption.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National State of International PatentApplication No. PCT/CN2017/077118 filed on Mar. 17, 2017, which claimspriority to Chinese Patent Application No. 201611037832.6 filed on Nov.23, 2016. Both of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the field of communications technologies,and in particular, to an identity authentication technology in aterminal.

BACKGROUND

With rapid development of information security technologies, peopleimpose increasingly high requirements on security, convenience, and highefficiency of identity authentication. However, because biologicalfeature information such as a fingerprint, a face, or voice is easilycopied or faked, an identity authentication manner that is based on thebiological feature information such as the fingerprint, the face, or thevoice has a disadvantage of relatively poor reliability. To overcome thedisadvantage, people propose a technology of performing identityauthentication by using a photoplethysmogram (photoelectricplethysmography, PPG) signal.

The PPG signal is a signal that is detected from a living tissue byusing a photoelectric means and that reflects a blood volume change. ThePPG signal has many advantages, for example, it is difficult to fake thePPG signal, and a user is unaware of a collection process. However,before identity authentication is performed based on a PPG signal, aconstant and stable PPG signal needs to be collected. Consequently, aPPG signal collection time is excessively long, and instant identityauthentication cannot be implemented. To meet a requirement for instantidentity authentication, a terminal periodically collects a PPG signal,so that when identity authentication needs to be performed based on aPPG signal, the PPG signal can be obtained in time. However, periodicPPG signal collection performed by the terminal occupies a relativelylarge quantity of resources, leading to excessively large powerconsumption.

SUMMARY

In view of this, this application provides a PPG authentication methodand a device, to improve timeliness of PPG authentication and reducepower consumption generated during PPG authentication.

According to one aspect, an embodiment of this application provides aPPG authentication method. In the method, a terminal detects whether aPPG signal pre-collection trigger condition is met currently, andcollects a current PPG signal of a user if the PPG signal pre-collectiontrigger condition is met currently. In this way, when it is detectedthat an application initiates a PPG authentication request, PPGauthentication is performed based on a most recently collected PPGsignal, thereby preventing timeliness of PPG authentication from beingaffected by an excessively long PPG signal collection time, and helpingimprove timeliness of PPG authentication. In addition, because theterminal collects a PPG signal only when the PPG signal pre-collectiontrigger condition is met, it indicates that the terminal collects a PPGsignal only when determining that there is to be a PPG authenticationneed, thereby avoiding resource consumption caused by periodic PPGsignal collection, and helping reduce power consumption.

In a possible design, the PPG signal pre-collection trigger conditionmay be: an application needing PPG authentication is started. Becauseafter the application needing PPG authentication is started, theapplication needing PPG authentication may initiate a PPG authenticationrequest, a PPG signal of the user is collected when the application isstarted. In this way, when the application initiates a PPGauthentication request, a PPG signal of the user is pre-collected, sothat PPG authentication can be directly performed by using thepre-collected PPG signal, thereby reducing a delay caused by real-timePPG signal collection, and ensuring timeliness of PPG authentication. Inaddition, a PPG signal is collected only when an application having aPPG authentication need is started, thereby avoiding excessively largepower consumption caused by periodic PPG signal collection, and helpingreduce power consumption of the terminal generated due to PPGauthentication.

In a possible design, the PPG signal pre-collection trigger conditionmay be: an application needing PPG authentication is started, and adistance between a current geographical location of the terminal and atarget geographical location is less than a first preset distancethreshold. The target geographical location is a geographical locationconfigured in the application, and the application initiates PPGauthentication at the target geographical location. In this way, afterthe application is started, and before the terminal arrives at thetarget geographical location at which the application needs to initiatePPG authentication, the terminal may pre-collect a PPG signal of theuser, so that when it is detected that the application initiates a PPGauthentication request, PPG authentication can be directly performedbased on the pre-collected PPG signal, thereby helping improvetimeliness of PPG authentication. In addition, the terminal collects aPPG signal only when it is determined, based on the distance between thegeographical location of the terminal and the target geographicallocation at which the application initiates PPG authentication, thatthere is a PPG authentication need currently, so that the terminal doesnot need to periodically collect a PPG signal, thereby reducing powerconsumption of the terminal.

In a possible design, the PPG signal pre-collection trigger conditionmay be: a time difference between a moment of executing a to-do list anda current moment is less than a first preset time threshold. When themoment of executing the to-do list arrives, an application executing theto-do list needs to initiate a PPG authentication request to theterminal. Therefore, before the moment of executing the to-do listarrives, the terminal pre-collects a PPG signal of the user, so thatwhen the application executing the to-do list initiates a PPGauthentication request, the terminal can directly complete PPGauthentication based on the pre-collected PPG signal, thereby improvingtimeliness of PPG authentication. In addition, the terminal collects aPPG signal only when it is determined that the moment of executing theto-do list is to arrive, and there is a PPG authentication needcurrently, thereby avoiding power consumption caused by periodic PPGauthentication collection of the terminal, and helping reduce powerconsumption of the terminal.

In a possible design, the PPG signal pre-collection trigger conditionmay be: a pre-trigger condition of an operation habit event, where amoment meeting the pre-trigger condition is earlier than a momentmeeting an occurrence condition of the operation habit event. In thiscase, the terminal may pre-collect a PPG signal of the user before theoperation habit event occurs, to avoid power consumption generated dueto periodic PPG signal collection, and help reduce power consumption ofthe terminal. In addition, after an application initiates a PPGauthentication request at the moment meeting the occurrence condition ofthe operation habit event, the terminal may directly perform PPGauthentication based on the pre-collected PPG signal, thereby improvingtimeliness of PPG authentication.

In a possible design, the PPG signal pre-collection trigger conditionmay include one or more of the foregoing, and may further includeanother trigger condition determined based on a use environment of theterminal, to determine, based on the use environment of the terminal,whether a PPG data collection module of the terminal needs to be startedin advance to collect a PPG signal.

In a possible design, that PPG authentication is performed based on themost recently collected PPG signal when the terminal detects the PPGauthentication request initiated by the application may be: performingmatching between the most recently collected PPG signal and a stored PPGtemplate signal, to complete PPG authentication. In this manner, whenthe terminal needs PPG authentication, the terminal performs PPGauthentication in real time by using the pre-collected PPG signal,thereby ensuring validity of a PPG authentication result, avoiding acase in which a PPG authentication result is invalid because a timelength between a moment of generating the PPG authentication result anda current moment is excessively large, and helping reduce resourceconsumption generated due to PPG authentication.

In a possible design, after the current PPG signal of the user iscollected, matching may be further performed between the collected PPGsignal and a stored PPG template signal, and a matching result is storedas a PPG authentication result, so that PPG authentication is completedin advance before an application initiates a PPG authentication request.In this way, if it is detected that the application initiates the PPGauthentication request, a most recently stored PPG authentication resultmay be directly invoked, thereby further reducing a time consumed forPPG authentication, and improving timeliness of PPG authentication.

According to another aspect, an embodiment of this application furtherprovides another PPG authentication method. The method is applied to awearable device. The wearable device pre-collects a first PPG signal ofa user, extracts first PPG feature data included in the first PPGsignal, establishes a PPG template based on the first PPG feature data,and stores the PPG template; maintains wearer identity information basedon wearing detection; detects a use environment of the user equipment;when determining, based on the use environment and current weareridentity information, that a PPG data collection module needs to bestarted in advance, starts the PPG data collection module, to collect asecond PPG signal of the user; and when the wearable device determinesthat PPG authentication currently needs to be performed, extracts secondfeature data based on the second PPG signal, and determines a matchingdegree between the extracted second feature data and the PPG template,to refresh the wearer identity information, to provide latest weareridentity information for a service application needing identityauthentication.

According to another aspect, an embodiment of this application furtherprovides a terminal. The terminal has a function of implementing actualterminal behavior in the foregoing method. The function may beimplemented by hardware, or by hardware executing correspondingsoftware. The hardware or software includes one or more modulescorresponding to the foregoing function.

In a possible design, the terminal includes a memory, a processor, and asensor. The processor is configured to support the terminal inperforming the corresponding function in the foregoing method. Thememory is configured to store a PPG signal pre-collection triggercondition, a PPG template signal, and the like in the foregoing PPGauthentication method. The memory is further configured to: be coupledto the processor, and store a program instruction and data that arenecessary for the terminal. The sensor is configured to support PPGsignal collection in the foregoing PPG authentication method.

According to another aspect, an embodiment of this application furtherprovides a PPG authentication apparatus. The apparatus includes adetection unit, a collection unit, and an authentication unit. Thedetection unit is configured to detect whether a PPG signalpre-collection trigger condition is met currently. The collection unitis configured to collect a current PPG signal of a user if the PPGsignal pre-collection trigger condition is met currently. Theauthentication unit is configured to: if it is detected that anapplication initiates a PPG authentication request, perform PPGauthentication based on the most recently collected PPG signal.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of thisapplication more clearly, the following briefly describes theaccompanying drawings required for describing the embodiments.Apparently, the accompanying drawings in the following description showmerely some embodiments of this application, and a person of ordinaryskill in the art may still derive other drawings from these accompanyingdrawings without creative efforts.

FIG. 1 is a schematic diagram of a compositional architecture of amobile phone according to this application;

FIG. 2 is a schematic diagram of a blood volume change detected based ona PPG;

FIG. 3 is a schematic flowchart of an embodiment of a PPG authenticationmethod according to this application;

FIG. 4A and FIG. 4B are a schematic flowchart of another embodiment of aPPG authentication method according to this application;

FIG. 5 is a schematic flowchart of another embodiment of a PPGauthentication method according to this application;

FIG. 6A and FIG. 6B are a schematic flowchart of another embodiment of aPPG authentication method according to this application; and

FIG. 7 is a schematic diagram of a compositional structure of anembodiment of a PPG authentication apparatus according to thisapplication.

DESCRIPTION OF EMBODIMENTS

A PPG authentication method in embodiments of this application isapplicable to a terminal. Specifically, the terminal may include but isnot limited to mobile terminals such as a mobile phone, a mobiletelephone, a mobile computer, a tablet computer, a personal digitalassistant (Personal Digital Assistant, PDA), a media player, anintelligent wearable device (for example, a smartwatch, a smart band,smart glasses, and a head-mounted intelligent device), an e-reader, ahandheld game console, and an in-vehicle electronic device, and mayfurther include intelligent devices such as a smart television and apoint of sales (Point of Sales, POS). The terminal specifically hasfunctions such as running an application (Application, APP) program,connecting to a network, and positioning.

That the terminal is a mobile phone is used as an example. FIG. 1 is aschematic diagram of a part of a compositional structure of a mobilephone 100 according to an embodiment of this application.

Referring to FIG. 1, the mobile phone 100 includes components such as aradio frequency (Radio Frequency, RF) circuit 110, a memory 120, aninput unit 130, a display unit 140, a sensor 150, an audio circuit 160,a Wireless Fidelity (wireless fidelity, WiFi) module 170, and aprocessor 180. The RF circuit 110, the memory 120, the input unit 130,the display unit 140, the sensor 150, the audio circuit 160, the WiFimodule 170, and the processor 180 are connected by using acommunications bus 190.

A person skilled in the art may understand that the structure of themobile phone shown in FIG. 1 does not constitute a limitation on themobile phone. The mobile phone may include more or fewer components thanthose shown in the figure, or may include a combination of somecomponents, or may include different component arrangements.

The following specifically describes the constituent components of themobile phone 100 with reference to FIG. 1.

The RF circuit 110 may be configured to: receive and send a signal in aninformation receiving or sending process or a call process.Particularly, the RF circuit 110 receives downlink information from abase station, then transmits the downlink information to the processor180 for processing, and sends uplink data to the base station. Usually,the RF circuit 110 includes but is not limited to: an antenna, at leastone amplifier, a transceiver, a coupler, a low noise amplifier (LowNoise Amplifier, LNA), and a duplexer. In addition, the RF circuit 110may communicate with a network and another device through wirelesscommunication. The wireless communication may use any communicationsstandard or protocol, including but not limited to: the Global Systemfor Mobile Communications (Global System of Mobile Communication, GSM),a general packet radio service (General Packet Radio Service, GPRS),Code Division Multiple Access (Code Division Multiple Access, CDMA),Wideband Code Division Multiple Access (Wideband Code Division MultipleAccess, WCDMA), Long Term Evolution (Long Term Evolution, LTE), ane-mail, and a short message service (Short Messaging Service, SMS).

The memory 120 may be configured to store a software program and amodule. For example, the memory may store data of a software programsuch as a positioning program in this application. The memory mayfurther store data in a PPG authentication process, for example, a PPGtemplate signal, information about a target geographical locationconfigured in an application, security level information bound to theapplication, operation habit information of a user, and to-do listinformation. In a possible implementation, the memory 120 may mainlyinclude a program storage area and a data storage area. The programstorage area may store an operating system, an application programrequired by at least one function (such as a sound playing function, animage playing function, and a positioning function), and the like. Thedata storage area may store data created based on use of the mobilephone 100, for example, audio data, an address book, and the operationhabit information of the user and the to-do list information that arementioned above.

In addition, the memory 120 may include a high-speed random accessmemory, or may include a nonvolatile memory, for example, at least onemagnetic disk storage component, a flash memory, or another volatilesolid-state storage component.

The input unit 130 may be configured to: receive entered digit orcharacter information, and generate key signal input related to usersetting and function control of the mobile phone 100. Specifically, theinput unit 130 may include a touch panel 131 and other input devices132. The touch panel 131 is also referred to as a touchscreen, maycollect a touch operation (for example, an operation performed by a,user on or near the touch panel 131 by using any suitable object oraccessory such as a finger or a stylus) of the user on or near the touchpanel 131, and drive a corresponding connection apparatus according to apreset program. In an implementation, the touch panel 131 may includetwo parts: a touch detection apparatus and a touch controller. The touchdetection apparatus detects a touch position of the user, detects asignal generated by the touch operation, and sends the signal to thetouch controller. The touch controller receives touch information fromthe touch detection apparatus, converts the touch information into touchpoint coordinates, and sends the touch point coordinates to theprocessor 180. Moreover, the touch controller can receive a command fromthe processor 180, and execute the command. In addition, the touch panelmay be implemented by using a plurality of types, such as a resistivetype, a capacitive type, an infrared ray, and a surface acoustic wavetype. In addition to the touch panel, the input unit 130 may includeother input devices. Specifically, the other input devices may includebut are not limited to: one or more of a physical keyboard, a functionkey (such as a volume control key or an on/off key), a trackball, amouse, and a joystick.

The display unit 140 may be configured to display information entered bythe user or information provided for the user, and various menus of themobile phone 100. The display unit 140 may include a display panel. In apossible case, the display panel may be configured by using a liquidcrystal display (Liquid Crystal Display, LCD), an organic light-emittingdiode (Organic Light-Emitting Diode, OLED), or the like. Further, thetouch panel may cover the display panel. After detecting a touchoperation on or near the touch panel, the touch panel sends the touchoperation to the processor 180, to determine a type of a touch event.Then, the processor 180 provides a corresponding visual output on thedisplay panel based on the type of the touch event. Although in FIG. 1,the touch panel and the display panel are used as two independentcomponents to implement input and input functions of the mobile phone100, in some embodiments, the touch panel and the display panel may beintegrated to implement the input and output functions of the mobilephone 100.

The mobile phone 100 may further include at least one sensor 150, forexample, a light sensor, a motion sensor, and another sensor.Specifically, the light sensor may include an ambient light sensor and aproximity sensor. The ambient light sensor may adjust luminance of thedisplay panel based on brightness of ambient light. The proximity sensormay turn off the display panel 141 and/or backlight when the mobilephone 100 approaches an ear. As a motion sensor, an accelerometer sensormay detect acceleration values in all directions (usually on threeaxes), may detect a value and a direction of gravity when theaccelerometer sensor is stationary, and may be applied to an applicationto recognize a mobile phone posture (for example, screen switchingbetween landscape and portrait modes, a related game, and magnetometerposture calibration), a function related to vibration recognition (suchas a pedometer and a knock), and the like.

Particularly, to collect a PPG signal used to reflect a blood volumechange of the user, the mobile phone may include a PPG sensor configuredto sense a PPG signal. A PPG data collection module configured tocollect PPG data is preset in the PPG sensor.

Other sensors such as a gyroscope, a barometer, a hygrometer, athermometer, and an infrared sensor may be configured in the mobilephone 100, and details are not described herein.

The audio circuit 160 may be connected to a loudspeaker and amicrophone, to provide an audio interface between the user and themobile phone 100. The audio circuit 160 may convert received audio datainto an electrical signal, and transmit the electrical signal to theloudspeaker. The loudspeaker converts the electrical signal into a soundsignal and outputs the sound signal. In addition, the microphoneconverts the collected sound signal into an electrical signal. The audiocircuit 160 receives the electrical signal, converts the electricalsignal into audio data, and then outputs the audio data to the RFcircuit 110, so that the RF circuit 110 sends the audio data to, forexample, another mobile phone, or outputs the audio data to the memory120 for further processing.

WiFi belongs to a short-range wireless transmission technology. Themobile phone 100 may help, by using the WiFi module 170, the user toreceive and send an email, browse a web page, access streaming media,and the like. The WiFi module 170 provides wireless broadband Internetaccess for the user. Although FIG. 1 shows the WiFi module 170, it maybe understood that the WiFi module is not a mandatory part of the mobilephone 100, and can be omitted based on a requirement without changingthe essence of the present invention.

The processor 180 is a control center of the mobile phone 100, connectsall parts of the entire mobile phone by using various interfaces andlines, and performs various functions of the mobile phone 100 andprocesses data by running or executing the software program and/or themodule stored in the memory 120 and invoking data stored in the memory120, to perform overall monitoring on the mobile phone.

In this embodiment of this application, the processor may be configuredto at least: detect whether a PPG signal pre-collection triggercondition is met currently; if the PPG signal pre-collection triggercondition is met currently, collect a current PPG signal of the user;and if it is detected that an application initiates a PPG authenticationrequest, perform PPG authentication based on the most recently collectedPPG signal. Specifically, the processor may be configured to implement aPPG authentication method provided in embodiments shown in FIG. 3 toFIG. 6A and FIG. 6B.

The processor 180 may include one or more processing units. In animplementation, an application processor and a modem processor may beintegrated into the processor 180. The application processor mainlyprocesses an operating system, a user interface, an application program,and the like. The modem processor mainly processes wirelesscommunication. It may be understood that the modem processor mayalternatively not be integrated into the processor 180.

The mobile phone 100 further includes a power supply (for example, abattery) for supplying power to the components. In a possible case, thepower supply may be logically connected to the processor 180 by using apower management system, to implement functions of charging,discharging, and power consumption management by using the powermanagement system.

Although not shown, the mobile phone 100 may further include apositioning module such as a GPS chip, and may obtain a currentgeographical location of the mobile phone by using the positioningmodule. Certainly, the mobile phone 100 may further include a camera, aBluetooth module, and the like, and details are not described herein.

It should be noted that the foregoing merely provides a description byusing an example in which the terminal is the mobile phone. However, itmay be understood that when the terminal is another mobile terminal orintelligent device, composition of the terminal may be similar to thatof the mobile phone, and details are not described herein.

The PPG authentication method in the embodiments of this application isa new biological feature identification method proposed based on a PPGtechnology. In the embodiments of this application, a signal that isdetected from a living tissue based on the PPG technology is referred toas a PPG signal. For ease of understanding, the PPG technology and thePPG signal required for authentication in this application are brieflydescribed.

The biological feature identification method proposed based on a PPG maybe simply referred to as PPG identification. The PPG identification hasthe following advantages:

A PPG signal is a signal inside a body, it is difficult to fake a PPGsignal, and the PPG signal has a good living feature and high security.

A characteristic of PPG detection is that the user is unaware of PPGdetection, and detection may be performed constantly. In addition,because of the characteristic that the user is unaware of PPG detectionand PPG detection may be performed constantly, a PPG signal may be usedas a constant identity certificate and applied to a wearable device suchas a smart band.

A PPG is easily combined with another external biological feature. Whena PPG sensor is combined with another contact biological feature sensor,for example, a fingerprint sensor, it is also suitable to use a PPG as aliving body detection feature and a second feature.

Currently, there are some paper researches on identity authenticationusing a PPG signal. For example, as early as in 2003, Yuanting, Zhang inthe Chinese University of Hong Kong has proposed that the followingseveral main variables of a PPG signal are used as parameters foridentity authentication:

(1) a slope K1 of a rising segment;

(2) a slope K2 of a falling segment;

(3) peak values PEAK of two wave peaks; and

(4) duration T1 of the rising segment.

FIG. 2 is a schematic diagram of a blood volume change detected based ona PPG. Several main variables reflecting a blood volume change aremarked in FIG. 2.

Accuracy of a final experimental result obtained after identityauthentication is performed based on the foregoing several mainvariables is up to 94%.

The PPG signal in the embodiments of this application may include anyone or more of the foregoing several parameters, and this is not limitedherein.

In the PPG authentication method in the embodiments of this application,a running environment of the terminal is detected, and when it isdetected that the terminal currently meets the PPG signal pre-collectiontrigger condition, collection of the current PPG signal of the user istriggered, to pre-obtain a PPG signal of the user before the applicationrequests PPG authentication. In this way, when it is detected that theapplication initiates a PPG authentication request, PPG authenticationcan be directly performed based on a most recently collected PPG signal,thereby preventing timeliness of PPG authentication from being affectedby an excessively long PPG signal collection time.

In addition, when the terminal currently meets the PPG signalpre-collection trigger condition, it indicates that the terminal is togenerate a PPG authentication need, so that a PPG signal is collectedonly when it is determined that there is a PPG authentication need,thereby avoiding resource consumption caused by periodic PPG signalcollection, and helping reduce power consumption.

The following describes, with reference to FIG. 1 by using an example inwhich a terminal is a smartwatch, a solution of a PPG authenticationmethod provided in an embodiment of this application.

FIG. 3 is a schematic flowchart of an embodiment of a PPG authenticationmethod according to this application. The method in this embodiment mayinclude the following steps.

S301. Collect a PPG signal of a user, and store the collected PPG signalas a PPG template signal required for matching during identityauthentication.

The smartwatch has a wearing accessory, for example, a watch chain, thatmay be worn on a part of the user such as a wrist. After the user wearsthe smartwatch, the PPG signal of the user may be collected by using aPPG sensor built in the smartwatch, and a processor of the smartwatchmay obtain, by using an interface connected to the PPG sensor, the PPGsignal of the user collected by the PPG sensor. The processor mayestablish a PPG template based on the collected PPG signal, and may usethe collected PPG signal as the PPG template signal required for asubsequent identity authentication process, so that during subsequentidentity authentication, matching is performed between a collectedto-be-matched PPG signal and the PPG template signal.

The generated PPG template signal may be stored in a memory.

In an implementation, the memory may include a PPG identificationmodule. The PPG identification module uses collected PPG data of theuser as a physiological feature of the user, to perform user identityidentification. Correspondingly, after the processor obtains, by usingthe interface, the PPG signal of the user collected by the PPG sensor ofthe watch, the processor runs or executes the PPG identification modulestored in the memory, to process the PPG signal, generate the PPGtemplate signal, and store the PPG template signal in the memory, sothat the PPG template signal is used for PPG signal matching in asubsequent authentication process.

The collected PPG signal may include one or more parameters mentionedabove and reflecting a blood volume change. In this embodiment of thisapplication, the PPG signal may be referred to as PPG data, and the PPGsignal and the PPG data essentially have a same meaning.

S302. Receive a security level configured by the user for anapplication, and store a correspondence between an applicationidentifier and the security level of the application.

For example, the user may perform a configuration operation in aconfiguration interface of the smartwatch or a configuration interfaceof the application, to configure security level information separatelyfor different applications. For example, a touchscreen (or another inputunit) of the smartwatch may receive a configuration operation that isentered by the user on the touchscreen of the smartwatch by using afinger or a stylus. The processor may determine, by identifying theconfiguration operation received on the touchscreen, a security levelconfigured by the user for an application.

The security level may include different levels. For example, thesecurity level may include a high security level and a low securitylevel. The high security level indicates that PPG authentication needsto be performed. To be specific, the PPG template signal establishedabove is a template configured for an application having a high securitylevel. The low security level indicates that another manner other thanPPG authentication may be used for identity authentication. Certainly,the security level may further include a security authentication-freelevel, and the security authentication-free level indicates that thereis no need to perform identity authentication. The applicationidentifier of the application is used to identify the application. Forexample, the application identifier may be a name, an identificationnumber, and the like of the application.

It may be understood that storing, based on a correspondence, theidentifier of the application and the security level configured by theuser for the application is merely a manner, and an objective of thismanner is to facilitate querying of the security level of theapplication when the application is subsequently started. However, inactual application, after the security level configured by the user forthe application is received, there may be another manner of querying thesecurity level corresponding to the application, and this is not limitedherein.

It may be understood that in this embodiment of this application, theuser configures the security level, to specify whether PPGauthentication needs to be performed for the application. However, inactual application, there may be another manner of specifying whetherPPG authentication is to be enabled for the application. For example, acorresponding option is provided for the user, so that the user chooseswhether to enable PPG authentication for the application. Another mannerof enabling PPG authentication for the application is also applicable tothis embodiment, and this is not limited herein.

It should be noted that step S301 and step S302 are merely descriptionsprovided for clearer and complete understanding of a PPG authenticationprocess. For example, step S301 is merely for clearer understanding of asource of a PPG template signal used in the PPG authentication process,and step S302 is how to determine whether an application has permissionfor PPG authentication. However, after a PPG template is stored and asecurity level of an application is set, there is no need to perform thetwo steps each time PPG authentication is performed. Particularly, whenall applications need to complete user identity authentication throughPPG authentication by default, there is no need to set security levelsof the applications. To be specific, there is no need to perform stepS302.

S303. If it is detected that an application is started, obtain anapplication identifier of the currently started target application.

A smartphone may monitor a start status of an application in thesmartphone, and obtain an application identifier of a currently startedapplication.

For example, an operation of starting an application by the user may bereceived by using the touchscreen of the smartwatch, and an obtainedstarting status of the application is transmitted to the processor.After receiving the starting status of the application, the processorobtains an application identifier of the started application by invokingan operating system interface in the memory.

It may be understood that identifying an application by using anapplication identifier of the application is merely an implementation,but is not an only implementation, provided that it can be identifiedwhich application in the smartwatch is a currently started applicationin actual application.

For ease of distinguishing, the currently started application isreferred to as a target application.

S304. Query, based on the application identifier of the targetapplication, whether a security level configured for the targetapplication indicates that the target application is an applicationneeding PPG authentication, and if the security level configured for thetarget application indicates that the target application is anapplication needing PPG authentication, perform step S305, or if thesecurity level configured for the target application indicates that thetarget application is not an application needing PPG authentication,perform step S308.

For example, if the security level configured by the user for thecurrently started application is a high security level, it indicatesthat the currently started application is an application for which PPGauthentication is enabled, and an operation required for subsequent PPGauthentication needs to be performed. Correspondingly, if the securitylevel corresponding to the currently started application is a lowsecurity level, it indicates that there is no need to perform PPGauthentication, and therefore a PPG signal of the user needs to bepre-collected.

Further, if the application is an application needing no PPGauthentication, when the processor detects that the applicationinitiates an authentication request, an operation of step S308 may beperformed, to perform authentication in a wearing detection manner. Fordetails, refer to descriptions of step S308.

S305. Detect whether an identity authentication result obtained afterthe smartwatch successfully performs PPG authentication most recentlystill meets time validity, and if the identity authentication resultmeets the time validity, determine that the authentication succeeds, andmaintain a PPG signal used for the most recent PPG authentication, or ifthe identity authentication result does not meet the time validity,perform step S306.

Certainly, when the authentication result of the most recent successfulPPG authentication meets the time validity, the result of the mostrecent PPG authentication may be maintained, so that the result of themost recent PPG authentication can be directly invoked subsequently, andthere is no need to perform matching between the PPG signal used for themost recent PPG authentication and the PPG template signal.

Time validity of an identity authentication result of PPG authenticationmay be a preset time length specified based on a requirement. Forexample, the time validity may be 10 minutes. Then, if a time lengthbetween a moment at which an operating system of the smartwatchsuccessfully performs PPG authentication most recently and a currentmoment is less than 10 minutes, it indicates that a most recent identityauthentication result is still a valid authentication result, and it maybe determined that PPG-based user identity authentication succeeds.

When the most recent authentication result meets the time validity, thePPG signal used for the most recent PPG authentication may not beupdated. In this way, if the smartwatch subsequently receives a PPGauthentication request initiated by any application, the PPG signal forthe most recent PPG authentication may be invoked, so that matching maybe performed between the PPG signal and the PPG template signal.Alternatively, the authentication result of the most recent PPGauthentication is maintained. In this way, when a PPG authenticationrequest initiated by an application is detected subsequently, theauthentication result of the most recent PPG authentication may beinvoked and returned to the application.

For example, after completing PPG authentication, the smartwatch maystore an identity authentication result of PPG authentication in thememory. Correspondingly, when the processor detects that an applicationis started, and the started application is an application needing PPGauthentication under configuration of the user, the processor initiatesa request to the memory, so that the processor accesses the memory, andinvokes the PPG identification module in the memory to determine whetheran identity authentication result of most recent successfulauthentication of the smartwatch meets the time validity, and if theidentity authentication result meets the time validity, directly returnsthe authentication result of the most recent PPG authentication to theapplication.

It should be noted that after it is determined that the targetapplication is an application needing PPG authentication, performingstep S305 is merely an implementation. In actual application, after itis determined that the target application is an application needing PPGauthentication, step S305 may not be performed and step S306 is directlyperformed.

S306. Collect a current PPG signal of the user, use the current PPGsignal as a to-be-authenticated PPG signal, and store theto-be-authenticated PPG signal.

If the currently started target application is an application needingPPG authentication, after the target application is started, a PPGsignal of the user is pre-collected. In this way, when the targetapplication requests PPG authentication, the PPG signal of the user iscollected, thereby preventing timeliness of PPG authentication frombeing affected by an excessively long signal collection time caused byreal-time PPG signal collection when the target application requests PPGauthentication.

For example, the smartwatch starts the PPG sensor, to collect a PPGsignal of the user at a current moment and store the PPG signal.Specifically, the processor invokes the PPG sensor by using theinterface, and starts a PPG data collection module in advance by usingthe PPG sensor, to collect the PPG signal of the user and store the PPGsignal in the memory.

S307. When a PPG authentication request initiated by an application isdetected, perform matching between a most recently storedto-be-authenticated PPG signal and the PPG template signal, to completePPG authentication.

The application may set, based on a requirement, a condition ofperforming PPG authentication. If the condition of PPG authentication ismet currently, a PPG authentication request may be submitted to theoperating system of the smartwatch. For example, when the user opens theapplication, PPG authentication needs to be performed, and the user canopen the application only when PPG authentication succeeds.Alternatively, when the user enters an interface of the application, PPGauthentication needs to be performed, and the user can enter theinterface only when PPG authentication succeeds.

Performing matching between the to-be-authenticated PPG signal and thePPG template signal may be as follows: The processor verifies whether asimilarity between the to-be-authenticated PPG signal and the PPGtemplate signal stored in the memory meets a requirement, and if thesimilarity between the to-be-authenticated PPG signal and the PPGtemplate signal exceeds a specified threshold, the processor maydetermine that the to-be-authenticated PPG signal matches the PPGtemplate signal. Specifically, it may be detected whether a similaritybetween one or more parameters used for identity authentication andincluded in the to-be-authenticated PPG signal and correspondingparameters in the PPG template signal exceeds a specified threshold.Correspondingly, if the to-be-authenticated PPG signal matches the PPGtemplate signal, the user identity authentication succeeds, or if theto-be-authenticated PPG signal does not match the PPG template signal,the user identity authentication fails.

It may be understood that each time the smartwatch detects that anapplication needing PPG authentication is started, the smartwatchtriggers PPG signal collection once. In this way, the smartwatch maystore a plurality of to-be-authenticated PPG signals. However, anapplication currently initiating a PPG authentication request may not bea target application that is started most recently. Therefore, toimprove PPG authentication accuracy, when an application initiates a PPGauthentication request, the smartwatch may obtain a most recently storedto-be-authenticated PPG authentication, and perform matching between themost recently stored to-be-authenticated PPG signal and the PPG templatesignal, to complete identity authentication.

Certainly, to reduce a data storage amount in the memory, the smartwatchmay store only a most recently collected to-be-authenticated PPG signal.In this case, when an application initiates a PPG authenticationrequest, the PPG signal stored in the smartwatch may be directly invokedand matching is performed between the stored PPG signal and the PPGtemplate.

It should be noted that step S307 is merely described by using anexample in which identity authentication is performed based on thestored to-be-authenticated PPG signal. In the manner of step S307, apre-collected and stored to-be-authenticated PPG signal is invoked formatching with the PPG template signal only when an application has aneed of performing identity authentication based on PPG identification(or needs a PPG identification function). However, it may be understoodthat in actual application, there may be a plurality of other possiblemanners of performing identity authentication based on theto-be-authenticated PPG signal.

For example, in another manner of performing user identityauthentication based on the to-be-authenticated PPG signal, when a PPGauthentication request of an application is detected, a time intervalbetween a current moment and a moment of storing the to-be-authenticatedPPG signal may be determined, and it may be determined whether the timeinterval is greater than a preset time threshold. If the time intervalis less than the preset time threshold, matching is performed betweenthe to-be-authenticated PPG signal and the PPG template signal, toperform user identity authentication. If the time interval is greaterthan the preset time threshold, a current PPG signal of the user isre-collected, and matching is performed between the currently collectedPPG signal and the PPG template signal, to perform user identityauthentication. In this manner, to improve identity identificationaccuracy, before identity authentication is performed based on thestored to-be-authenticated PPG signal, it needs to be determined whetherthe to-be-authenticated PPG signal exceeds the preset time threshold, toensure validity of the to-be-authenticated PPG signal.

The preset time threshold may be set based on a requirement. It shouldbe noted that the operating system of the smartwatch may use a same timethreshold for different applications, or store a time thresholdcorresponding to each application. For example, the user may set, basedon a security level required by an application, a time threshold allowedby the application in the operating system or the application, and thesmartwatch stores a time threshold of each application. Particularly,when each application corresponds to a different time threshold, if aPPG authentication request initiated by an application is detected,after the time interval between the current moment and the moment ofstoring the to-be-authenticated PPG signal is determined, it may bedetermined whether the time interval is greater than a time thresholdcorresponding to the application initiating the PPG authenticationrequest. In another manner of performing user identity authenticationbased on the to-be-authenticated PPG signal, after theto-be-authenticated PPG signal is collected, matching may be directlyperformed between the to-be-authenticated PPG signal and the PPGtemplate signal, to perform user identity authentication, and anauthentication result is stored as a PPG authentication result. If thePPG authentication request of the application is detected (for example,it is detected that a PPG identification function is invoked), when PPGauthentication needs to be performed, a most recently stored PPGauthentication result may be invoked and returned to the application.

It may be understood that after a PPG authentication result is obtainedin step S307, the processor may further return the PPG authenticationresult to the application initiating the PPG authentication request.

S308. If an application needing no PPG authentication initiates anauthentication request, detect whether the smartwatch is always in aworn state within a time period between a moment at which PPGauthentication on the user succeeds most recently and a current moment,and when it is detected that the smartwatch is always in the worn state,determine that user identity authentication succeeds.

In this embodiment of this application, identity authentication isperformed through wearing detection. This case is applicable to anintelligent device that can be worn on a part of a body of the user, forexample, a smartwatch and a head-mounted intelligent device. Wearingdetection means that it is detected, by using a proximity sensor or abuckle, whether the smartwatch of the user is in a worn state or ataken-off state. For example, it is detected, by using the proximitysensor or the buckle, whether the smartwatch is not in contact withskin. If the smartwatch is in contact with the skin, it is determinedthat the smartwatch of the user is in the worn state. If it is detectedthat the smartwatch of the user is not in contact with the skin, it isdetermined that the smartwatch of the user is in the taken-off state.For an application having a low security level, after the smartwatchperforms PPG authentication on the user and determines that PPGauthentication on the user succeeds, if the user never takes off thesmartwatch, it indicates that a wearer wearing the smartwatch does notchange. In this case, it may be considered that identity informationauthentication on the wearer succeeds. If the smartwatch is not in theworn state, or if the wearer takes off the smartwatch within a timeperiod between a moment at which PPG authentication of the targetapplication on the user succeeds most recently and a current moment,identity information authentication on the wearer fails.

It may be understood that this embodiment of this application isdescribed by using an example in which identity authentication isperformed, through wearing detection, for the target application havinga low security level. However, a person skilled in the all mayunderstand that another manner used for identity authentication for theapplication having the low security level is also applicable to thisapplication. For example, identity authentication may be performed,based on a password, a fingerprint, and the like, for the applicationhaving the low security level. For another example, there may be no needto perform identity authentication for the application having the lowsecurity level.

In this embodiment, when it is determined that the currently startedapplication is an application needing PPG authentication, the currentPPG signal of the user may be collected and stored. In this way, whenPPG authentication needs to be performed for the application, matchingmay be directly performed based on the collected and stored PPG signaland the PPG template signal, to perform user identity authentication,thereby preventing timeliness of PPG authentication from being affectedby an excessively long PPG signal collection time, and ensuringtimeliness of PPG authentication.

In addition, the PPG signal is collected only when it is determined thatthe application is started and PPG authentication needs to be performedfor the application, thereby avoiding resource consumption caused byperiodic PPG signal collection, and helping reduce power consumption.

It may be understood that in the embodiment of FIG. 3, a PPG signal of auser is pre-collected before PPG authentication needs to be performedfor an application. However, it may be understood that there may be aplurality of PPG signal pre-collection trigger conditions, and FIG. 3 ismerely described by using one of the PPG signal pre-collection triggerconditions as an example. In actual application, there may be anothercondition of triggering pre-collection of a PPG signal of the user. Forexample, FIG. 4A and FIG. 4B are a schematic flowchart of anotherembodiment of a PPG authentication method according to this application.The method in this embodiment may include the following steps.

S401. A smartwatch collects a PPG signal of a user, and stores thecollected PPG signal as a PPG template signal required for matchingduring identity authentication.

For step S401, refer to the related descriptions of step S301, anddetails are not described herein again.

S402. If it is detected that a preset target application needing PPGauthentication is started, obtain a target geographical locationconfigured in the target application.

The target application may be set based on a requirement. There may beone or more target applications. For example, a plurality ofapplications having a relatively high security requirement and relatedto transfer, payment, check-in, and the like are set as applicationsneeding PPG authentication. For example, identifier information and thelike of each target application may be stored in a memory. Afterdetecting that an application is started, a processor may query thememory to verify whether an identifier of the currently startedapplication is an identifier that is stored in the memory and that is ofan application needing PPG authentication.

A manner in which the processor detects that the target application isstarted may be that the processor detects that there is an operationused to trigger starting of the target application on a touchscreen, orthe processor detects, by using an interface, that the application isstarted. For details, refer to the related descriptions of the foregoingembodiment.

The target geographical location configured in the target applicationmay be preset, and when the smartwatch arrives at the targetgeographical location, a PPG authentication function usually needs to beenabled. For example, the target application may be taxi hailingapplication software. When fare payment is made by using the taxihailing application software, user identity authentication needs to beperformed based on PPG identification. Then, the user may set a homeaddress, a company location, or the like of the user as a targetgeographical location, so that collection of a PPG signal of the user istriggered in advance before the user subsequently arrives at the targetgeographical location. For another example, the target application maybe a payment application. Then, the user may set, as a targetgeographical location, a location at which the user usually needs to payevery day. For example, a convenience store, a supermarket, a cinema, orthe like is set as a target geographical location.

The target geographical location configured in the target applicationmay be determined in real time. For example, the target application is ataxi hailing application. Then, after the user starts the taxi hailingapplication, the user may enter a destination. In this case, informationabout the destination received by the target application may beobtained, and the destination is set as a target geographical location.

Certainly, there may be another manner of setting a target geographicallocation, and this is not limited herein.

After the target geographical location is set in the smartwatch by usingan input interface such as the touchscreen, the processor may store, inthe memory, a correspondence between the target geographical locationcollected by using the input interface and the target application. Inthis way, when the target application is started, the processor mayinvoke, from the memory, information about the target geographicallocation configured in the target application.

S403. Obtain a current geographical location of the smartwatch.

It may be understood that the current geographical location of thesmartwatch is a current geographical location of the user wearing thesmartwatch.

For example, the processor of the smartwatch may obtain the currentgeographical location of the smartwatch by using a positioning module ofthe smartwatch. For example, the processor invokes a GPS module toperform positioning, and after the GPS obtains positioning data, theprocessor obtains the positioning data collected by the GPS.

S404. Detect whether a distance between the current geographicallocation of the smartwatch and the target geographical location is lessthan a preset distance threshold, and if the distance is less than thepreset distance threshold, perform step S405, or if the distance is notless than the preset distance threshold, perform step S403.

For example, the processor compares information about the geographicallocation collected by the positioning module of the smartwatch andinformation about the target geographical location that is configured inthe target application and that is stored in the memory, and determineswhether the distance between the current geographical location of thesmartwatch and the target geographical location stored in the memory isless than the preset distance threshold, to determine whether thesmartwatch currently is close to or is to arrive at the targetgeographical location.

It should be noted that for ease of distinguishing between the presetdistance threshold and a subsequent distance threshold, the presetdistance threshold in this embodiment may be referred to as a firstpreset distance threshold.

S405. If the distance between the current geographical location of thesmartwatch and the target geographical location is less than the presetdistance threshold, determine whether a service type bound to the targetgeographical location is a service type needing PPG authentication, andif the service type is a service type needing PPG authentication,perform step S406, or if the service type is not a service type needingPPG authentication, perform step S410.

After the distance between the current geographical location of thesmartwatch and the target geographical location is determined, thedistance is compared with the preset distance threshold. If the distanceis less than the distance threshold, it indicates that the user is toarrive at the target geographical location.

It may be understood that one application may perform a plurality ofdifferent services. For example, in addition to a transfer service, apayment service, and the like, a payment application may implementservices such as interface unlocking authentication and instantmessaging. For an application, the user may perform different servicesat different target geographical locations. Therefore, in thisapplication, different target geographical locations may be bound todifferent service types. For example, the memory stores service typesbound to different target geographical locations. Different servicetypes require different security levels. The smartwatch may preset, as aservice type needing PPG authentication, a service type having arelatively high security level requirement. For example, a paymentservice usually has a relatively high security level requirement.Therefore, if a service type is a payment service, PPG authenticationneeds to be performed. To be specific, a PPG template is set for thepayment service, and during authentication, matching is performedbetween a collected. PPG signal of the user and a PPG template signal.Services such as interface unlocking authentication and instantmessaging have relatively low security level requirements, and theservices are set as service types needing no PPG authentication, so thatthere is no need to trigger a subsequent operation of pre-collecting aPPG signal of the user, and when an application initiates identityauthentication for this service type, identity authentication may beperformed in the wearing detection manner described above.

It should be noted that if the distance between the current geographicallocation of the smartwatch and the target geographical location is lessthan the preset distance threshold, the “determining whether a servicetype bound to the target geographical location is a service type needingPPG authentication” is not a necessary step. When the target applicationincludes a single service type, or a service type that may be performedby the target application requires a relatively high security level, anoperation of pre-collecting a PPG signal of the user can be triggeredprovided that the user is to arrive at the target geographical location,and there is no need to determine whether the service type is a servicetype needing PPG authentication.

S406. Detect whether an identity authentication result obtained afterthe smartwatch successfully performs PPG authentication most recentlystill meets time validity, and if the identity authentication resultmeets the time validity, determine that the authentication succeeds, andmaintain a most recent PPG authentication result, or if the identityauthentication result does not meet the time validity, perform stepS407.

It may be understood that in this embodiment of this application, whenPPG authentication is performed by performing matching between a mostrecently stored PPG signal and the PPG template signal when a PPGauthentication request initiated by an application is subsequentlydetected, when it is determined that the most recent PPG authenticationsuccess result meets the time validity, a PPG signal used for mostrecent PPG authentication may be maintained, so that there is no need tore-collect a PPG signal.

For step S406, refer to the related descriptions of step S305, anddetails are not described herein again.

Similar to step S305, in this embodiment, when it is determined that thecurrent geographical location of the smartwatch is to coincide with thetarget geographical location, and it is determined that the service typeis a service type needing PPG authentication, step S407 may be directlyperformed and step S406 may be skipped.

S407. Collect a current PPG signal of the user, and use the PPG signalas a to-be-authenticated PPG signal.

In an implementation, after the to-be-authenticated PPG signal iscollected, the to-be-authenticated PPG signal may be further stored.

S408. Perform matching between the to-be-authenticated PPG signal andthe PPG template signal, obtain a PPG authentication result, and storethe PPG authentication result.

S409. When a PPG authentication request initiated by an application isdetected, invoke a most recently stored PPG authentication result.

It may be understood that step S408 and step S409 are described by usingan example in which identity authentication is performed based on thestored to-be-authenticated PPG signal. However, it may be understoodthat another implementation of performing identity authentication basedon the stored to-be-authenticated PPG signal in the embodiment of FIG. 3is also applicable to this embodiment, and details are not describedherein again.

S410. If a non-PPG authentication identity authentication requestinitiated by an application is detected, detect whether the smartwatchis always in a worn state within a time period between a moment at whichPPG authentication of the target application on the user succeeds mostrecently and a current moment, and when it is detected that thesmartwatch is always in the worn state, determine that user identityauthentication succeeds.

For example, if an application needing no PPG authentication initiatesan identity authentication request, or an application initiates anidentity authentication request when performing a service needing no PPGauthentication, the identity authentication request is not a PPGauthentication request. Therefore, an intelligent terminal may performidentity authentication through wearing detection.

For a specific process of step S410, refer to the related descriptionsof step S308 in the foregoing embodiment, and details are not describedherein again.

In this embodiment of this application, when it is detected that thetarget application needing PPG authentication is started, the targetgeographical location configured in the target application is obtained.If the distance between the geographical location of the smartwatch andthe target geographical location is less than the preset distancethreshold, the smartwatch collects the current PPG signal of the user asthe to-be-authenticated PPG signal. In this way, when the smartwatcharrives at the target geographical location and needs to perform PPGauthentication, PPG authentication may be directly performed based onthe collected to-be-authenticated PPG signal, thereby reducing a case inwhich timeliness of PPG authentication is affected by an excessivelylong PPG signal collection time. In addition, when it is determined thatthe distance between the current geographical location of the smartwatchand the target geographical location is less than the preset distancethreshold, it may indicate that the target application is to need PPGauthentication. In this way, before needing to perform PPGauthentication, the smartwatch collects the to-be-authenticated PPGsignal required for PPG authentication, thereby avoiding resourceconsumption caused by periodic PPG signal collection, and helping reducepower consumption.

For ease of understanding of the solution of the embodiment shown inFIG. 4A and FIG. 4B, the following describes the solution of thisembodiment in this application with reference to several applicationscenarios.

First, a description is provided by using an example in which the targetapplication is taxi hailing software. When the user travels, the useropens the taxi-hailing software to hail a taxi, and enters a destination“Kunming Zoo” in the taxi hailing software. Then, the smartwatch detectsthat the taxi hailing software is started, and obtains a targetgeographical location “Kunming Zoo”. The smartwatch detects a currentgeographical location of the smartwatch, and compares the geographicallocation of the smartwatch with the destination. If the geographicallocation of the smartwatch is to coincide with the destination (forexample, the smartwatch is further 0.5 kilometers away from thedestination), the smartwatch starts a PPG data collection module inadvance to collect a current PPG signal of the user. In this way, afterarriving at the destination, the smartwatch can perform identityauthentication based on the pre-collected PPG signal (for example,perform matching between the pre-collected PPG signal and the PPGtemplate signal, or obtain a PPG authentication result obtained aftermatching is performed between the PPG signal and the PPG templatesignal) when receiving a PPG authentication request of the taxi hailingsoftware, to complete identity authentication during fare payment.

For another example, for a payment application, in consideration ofsecurity, identity authentication needs to be performed based on a PPGsignal during payment. A target geographical location preset in thepayment application may be an entrance to a convenience store, a cinema,or a supermarket. After the smartwatch detects that the paymentapplication is started, the smartwatch detects a distance between ageographical location of the smartwatch and any target geographicallocation. If a distance between a current geographical location of thesmartwatch and a target geographical location is less than a presetdistance threshold, it indicates that the user is to arrive at a placeat which payment needs to be made, for example, the cinema, thesupermarket, or the convenience store. Therefore, to ensure timelyidentity authentication during payment, the smartwatch pre-collects aPPG signal of the user before arriving at the target geographicallocation at which payment needs to be made, and performs paymentauthentication based on the pre-collected PPG signal when paymentauthentication needs to be performed. In this way, not only timelinessof payment authentication is ensured, but also power consumption causedby periodic PPG signal collection can be reduced.

Certainly, for some applications having a punch-in/out function, acompany address may be set as a target geographical location. In thisway, when a terminal device detects that the user is near to thecompany, the terminal device may pre-collect a PPG signal of the user,so that when the terminal device needs to be unlocked for punch-in/out,PPG authentication may be directly performed by using the collected PPGsignal, thereby verifying validity of the user identity.

The following describes, by using another PPG signal pre-collectiontrigger condition as an example, another application scenario to whichthe PPG authentication method in this application is applicable. Forexample, FIG. 5 is a schematic flowchart of another embodiment of a PPGauthentication method according to this application. The method in thisembodiment still uses an example in which the method is applied to asmartwatch. The method in this embodiment may include the followingsteps.

S501. Collect a PPG signal of a user, and store the collected PPG signalas a PPG template signal required for matching during identityauthentication.

For step S501, refer to the descriptions of the corresponding step inthe foregoing embodiment, and details are not described herein again.

S502. Obtain and store operation habit information of the user.

An operation habit of the user may reflect a moment or a location atwhich PPG authentication needs to be performed on the user, or a case inwhich PPG authentication needs to be performed on the user. Therefore,collecting the operation habit information of the user helps start,subsequently based on an operation habit of the user, a PPG datacollection module in a PPG sensor in advance to collect a PPG signal ofthe user, so that the PPG signal of the user may be pre-collected beforePPG authentication needs to be performed. The operation habit of theuser may be obtained by a processor by collecting and extractinginformation about operation behavior of the user in an application.After obtaining the operation habit information of the user throughanalysis, the processor may store the operation habit information of theuser in a memory.

In this embodiment of this application, the operation habit informationmay include an operation habit of the user and a condition of triggeringthe operation habit. For example, the operation habit information of theuser may include the following several possible cases.

In a possible case, the operation habit information may be an eventoperation performed based on a time. For example, the user goes torestaurants for dining at 8 o'clock am and 12 o'clock am, and pays ameal fee by using payment software in the smartwatch, and identityauthentication is performed based on a PPG signal during meal feepayment.

In another possible case, the operation habit information may be anevent operation performed based on a frequent destination. For example,frequent destinations such as a gasoline station, a bakery, aconvenience store, and a subway station that the user usually goes toare recorded. Identity authentication needs to be performed on the userbased on a PPG signal of the user at the frequent destinations, tocomplete payment, identity authentication, or the like.

In another possible case, the operation habit information may be anevent operation triggered by a key word entered by the user. Forexample, the user enters key words such as a supermarket name, a productname, a name of a recently shown film, and borrowing some money, totrigger a need of performing identity authentication on the user basedon a PPG signal of the user, to complete identity authenticationrequired for operations, for example, the user buys a product, buys amovie ticket, and makes a transfer.

In another possible case, the operation habit information may be anoperation record of the user, for example, an operation record of theuser in an application such as an operation record of the user during agame (the operation habit information may be used to predict whether theuser buys game items, so that a PPG signal required for user identityauthentication is collected before the user buys the game items), and anexercise record of the user (used to predict whether the user is boundto exercise data through identity authentication, so that a PPG signalrequired for identity authentication is obtained before identityauthentication).

Certainly, the foregoing merely lists several possible cases of theoperation habit information. In actual application, there may be aplurality of other cases of the operation habit information, and this isnot limited herein.

S503. Detect, based on the stored operation habit information, whether apre-trigger condition of an operation habit event is met currently, ifthe pre-trigger condition is met currently, perform step S504, or if thepre-trigger condition is not met currently, continue to perform stepS503.

For an operation habit event, a pre-trigger condition of the operationhabit event and an occurrence condition of the operation habit eventmeet a particular relationship, and usually, a moment meeting thepre-trigger condition of the operation habit event is earlier than amoment meeting the occurrence condition of the operation habit event.

For example, the pre-trigger condition of the operation habit eventincludes any one or more of the following:

a time difference between a moment at which the operation habit eventoccurs and a current moment is less than a preset time threshold; and

a distance between a current geographical location of a terminal and alocation at which the operation habit event occurs is less than a secondpreset distance threshold. For ease of distinguishing between the secondpreset distance threshold and the foregoing first preset distancethreshold, the distance threshold specified in this embodiment isreferred to as a second preset distance threshold. However, it may beunderstood that values of the first preset distance threshold and thesecond preset distance threshold may be the same or may be different.

Certainly, the pre-trigger condition of the operation habit event mayalternatively be the occurrence condition of the operation habit event.

The occurrence condition of the operation habit event may be a moment, alocation, or the like at which occurrence of the operation habit eventis triggered. For example, if the operation habit information is buyingbreakfast by using payment software at 8 o'clock am every day, if it isdetected that a current moment is 8 o'clock am, it indicates that anoccurrence condition of buying breakfast by using the payment softwareis met currently. For another example, if the operation habitinformation is that identity authentication is performed on the user byusing a particular application at a specified office location, if it isdetected that a current location is the specified office location, itindicates that an occurrence condition of performing identityauthentication by using the application is met currently.

S504. Determine a service type of a service operation triggered by atarget operation habit event meeting an occurrence condition, detectwhether the service type is a service type needing PPG authentication,and if the service type is a service type needing PPG authentication,perform step S505, or if the service type is not a service type needingPPG authentication, perform step S508.

For ease of distinguishing, in this embodiment, an operation habitcurrently meeting the occurrence condition is referred to as a targetoperation habit.

Different operation habits may trigger different service operations. Forexample, the service operations may be punching in/out, shopping,transferring, and unlocking. Similar to the embodiment of FIG. 4A andFIG. 4B, the service operations may be classified into a plurality ofservice types, and different service types may be classified into twocategories. One is a service needing PPG authentication, and forexample, may be specifically a service having a high security level. Theother is a service type needing no PPG authentication. For example, theservice type may include a payment service having a relatively highsecurity level requirement. If a service operation triggered by anoperation habit is a payment service, PPG authentication needs to beperformed. The service type may further include a service needing no PPGauthentication, for example, an unlocking service having a relativelylow security level requirement.

It should be noted that “determining whether the service type triggeredby the target operation habit is a service type needing PPGauthentication” is not a necessary step, and when each collected targetoperation habit is an operation habit that may trigger a service typeneeding PPG authentication, there is no need to determine whether theservice type is a service type needing PPG authentication.

S505. Detect whether an identity authentication result obtained afterthe smartwatch successfully performs PPG authentication most recentlystill meets time validity, and if the identity authentication resultmeets the time validity, determine that the authentication succeeds, andmaintain a PPG signal used for the most recent PPG authentication, or ifthe identity authentication result does not meet the time validity,perform step S506.

For step S505, refer to the related descriptions of step S305, anddetails are not described herein again.

Similar to step S305, in this embodiment, step S506 may be directlyperformed and step S505 may be skipped.

S506. Collect a current PPG signal of the user, use the current PPGsignal as a to-be-authenticated PPG signal, and store theto-be-authenticated PPG signal.

S507. When a PPG authentication request initiated by an application isdetected, perform matching between the stored to-be-authenticated PPGsignal and a PPG template signal, to perform user identityauthentication.

It may be understood that step S507 is described by using an example inwhich identity authentication is performed based on the storedto-be-authenticated PPG signal. However, it may be understood thatanother implementation of performing identity authentication based onthe stored to-be-authenticated PPG signal in the embodiment of FIG. 3 isalso applicable to this embodiment, and details are not described hereinagain.

S508. If a non-PPG authentication identity authentication requestinitiated by an application is detected, detect whether the smartwatchis always in a worn state within a time period between a moment at whichthe smartwatch successfully performs PPG authentication on the user mostrecently and a current moment, and when it is detected that thesmartwatch is always in the worn state, determine that user identityauthentication succeeds.

For example, when an application performs a service operation needing noPPG authentication, an authentication request initiated by theapplication may be a common identity authentication request needing noPPG authentication.

It may be understood that in a process of performing step S503 to stepS508, user operation habits may be recorded constantly, so that anoccurrence condition of an operation habit is dynamically adjusted basedon a change of the user operation habit. Correspondingly, after theoccurrence condition of the operation habit is adjusted, a startoccasion of a PPG identification module may be adjusted.

The following describes a PPG authentication method in this applicationby using another condition of triggering pre-collection of a PPG signalof a user as an example. For example, FIG. 6A and FIG. 6B are aschematic flowchart of another embodiment of a PPG authentication methodaccording to this application. The method in this embodiment still usesan example in which the method is applied to a smartwatch. The method inthis embodiment may include the following steps.

S601. Collect a PPG signal of a user, and store the collected PPG signalas a PPG template signal required for matching during identityauthentication.

For step S601, refer to the descriptions of the corresponding step inthe foregoing embodiment, and details are not described herein again.

S602. Obtain a to-do list specified by the user, and store the to-dolist.

The to-do list is some reminders that are specified by the user and thatneed to be processed after a current moment. For example, the userenters some to-do lists in an application interface of an application byusing an input interface such as a touchscreen. After collectinginformation about the to-do lists entered by using the input interface,a processor invokes an interface provided by a memory, to store theto-do lists specified by the user.

The to-do list may have a plurality of forms. For example, the to-dolist may include a recharging prompt (for example, a recharging promptfor arrears), a rent payment prompt, and scheduling. For example, thescheduling may include “going to a movie at 3 o'clock pm” or “boardingthe plane for Xi'an at 3 o'clock pm”, or may be “going to a supermarketto buy milk at 5 o'clock pm”.

It may be understood that the user may set a plurality of to-do lists.In this embodiment of this application, the to-do lists may be stored ina form of a list.

S603. Determine a time of executing the to-do list and a type of theto-do list based on content of the to-do list, and store the time ofexecuting the to-do list and the type of the to-do list.

The type of the to-do list is used to indicate whether the to-do listneeds identity authentication. For example, the to-do list may beclassified into two categories. One is a to-do list needing real-timeidentity authentication, and the other is a to-do list needingnon-real-time identity authentication. PPG authentication needs to beperformed in a process of executing a to-do list needing real-timeidentity authentication. To be specific, a PPG template is preset.During authentication, matching is performed between collected PPG dataand the PPG template, and if a matching threshold is reached, PPGauthentication succeeds, or if a matching threshold is not reached, PPGauthentication fails. There is no need to perform PPG authentication ina process of executing a to-do list needing non-real-time identityauthentication. For example, authentication may be performed onlythrough wearing detection mentioned above.

There may be a plurality of manners of determining the type of the to-dolist.

For example, in a possible case, the processor may determine the type ofthe to-do list based on a key word included in the to-do list. Forexample, a correspondence between different key words and types of to-dolists may be preset in the memory. In this way, the processor determinesthe type of the to-do list based on the correspondence stored in thememory and a key word included in the to-do list. For example, it isassumed that the to-do list includes a key word such as “shopping” or“supermarket”. It indicates that the smartwatch needs to perform PPGauthentication on the user when executing the to-do list, and when it isdetected that the to-do list includes “shopping” or “supermarket”, it isdetermined that the type of the to-do list is an item type needing PPGauthentication.

In another possible case, the type of the to-do list is set or includedin content of the to-do list stored in the memory. In this case, theprocessor may directly extract the type of the to-do list frominformation about the to-do list stored in the memory. For example, theto-do list is recharging, and a type of the recharging item may be anitem needing PPG authentication. Then, when storing the to-do list, thememory may store an item type of the to-do list as an item needing PPGauthentication, and the processor may directly invoke the memory toquery the type of the to-do list.

Certainly, there may be another manner of determining the type of theto-do list, and this is not limited herein.

S604. Detect whether the stored to-do list includes a target to-do list,where a time length between a time of executing the target to-do listand a current moment is less than a preset time threshold, and if thestored to-do list includes the target to-do list, perform step S605, orif the stored to-do list does not include the target to-do list,continue to monitor the to-do list.

The preset time threshold may be set based on a requirement. Forexample, the preset time threshold may be 1 minute. In this way, if atime difference between a time of executing a to-do list and a currentmoment is less than 1 minute, it indicates that the to-do list is ato-be-processed target to-do list. S605. Detect, based on a type of thetarget to-do list, whether the target to-do list is a to-do list needingPPG authentication, and if the target to-do list is a to-do list needingPPG authentication, perform step S606, or if the target to-do list isnot a to-do list needing PPG authentication, perform step S609.

It may be understood that when each stored to-do list is a to-do listneeding PPG authentication, there is no need to perform step S603 ofdetermining the type of the to-do list and detecting whether the type ofthe target to-do list is a to-do list needing PPG authentication. Inthis case, step S606 may be directly performed and step S605 may beskipped.

It should be noted that the preset time threshold in step S604 may bethe same as or different from the present time threshold in step S503.For ease of distinguishing, in this embodiment of this application, thepreset time threshold in step S604 may be referred to as a first presettime threshold and the preset time threshold in step S503 may bereferred to as a second preset time threshold.

S606. Detect whether an identity authentication result of most recentsuccessful PPG authentication still meets time validity, and if theidentity authentication result meets the time validity, determine thatthe authentication succeeds, or if the identity authentication resultdoes not meet the time validity, perform step S607.

For step S606, refer to the related descriptions of step S305, anddetails are not described herein again.

Similar to step S305, in this embodiment, step S607 may be directlyperformed and step S606 may be skipped.

S607. Collect a current PPG signal of the user, use the current PPGsignal as a to-be-authenticated PPG signal, and store theto-be-authenticated PPG signal.

S608. When a PPG authentication request initiated by an application isdetected, perform matching between the stored to-be-authenticated PPGsignal and a PPG template signal, to perform user identityauthentication.

In this embodiment of this application, the PPG authentication requestinitiated by the application may be a PPG authentication request that isinitiated when the application configured to execute a target to-do listdetects that a condition of executing, by the application, the targetto-do list is met currently, or may be a PPG authentication request thatis initiated by any application in the smartwatch to an operating systemof the smartwatch when the application needs PPG authentication.

It may be understood that step S608 is described by using an example inwhich identity authentication is performed based on the storedto-be-authenticated PPG signal. However, it may be understood thatanother implementation of performing identity authentication based onthe stored to-be-authenticated PPG signal in the embodiment of FIG. 3 isalso applicable to this embodiment, and details are not described hereinagain.

S609. Detect whether the smartwatch is always in a worn state within atime period between a moment at which the smartwatch successfullyperforms PPG authentication on the user most recently and a currentmoment, and when it is detected that the smartwatch is always in theworn state, determine that user identity authentication succeeds.

For step S609, refer to the related descriptions in the foregoingembodiment, and details are not described herein again.

It should be noted that the foregoing embodiments of this applicationeach are described by using one PPG signal pre-collection triggercondition as an example. However, it may be understood that in actualapplication, the PPG signal pre-collection trigger condition may includeone or more of the foregoing trigger conditions. In this case, thememory may store one or more PPG signal pre-collection triggerconditions at the same time, and when detecting whether any one or morePPG signal pre-collection trigger conditions stored in the memory aremet currently, the processor may invoke an interface of a sensor, totrigger the sensor to collect a current PPG signal of a user.

In addition, the foregoing embodiments of this application are describedby using an example in which the terminal is a smartwatch. However, itmay be understood that when the terminal is a mobile terminal such as amobile phone, or a wearable intelligent device such as a head-mountedintelligent terminal, the foregoing embodiments are also applicable.

In addition, an embodiment of this application provides a PPGauthentication apparatus. FIG. 7 is a schematic diagram of acompositional structure of an embodiment of the PPG authenticationapparatus according to this application. The apparatus in thisembodiment may include:

a detection unit 701, configured to detect whether a PPG signalpre-collection trigger condition is met currently;

a collection unit 702, configured to: if the PPG signal pre-collectiontrigger condition is met currently, collect a current PPG signal of auser; and

an authentication unit 703, configured to perform PPG authenticationbased on the most recently collected PPG signal if it is detected thatan application initiates a PPG authentication request.

In a possible implementation, the detection unit is specificallyconfigured to detect whether any one or more PPG signal pre-collectiontrigger conditions of the following are met currently:

an application needing PPG authentication is started;

an application needing PPG authentication is started, and a distancebetween a current geographical location of a terminal and a targetgeographical location is less than a first preset distance threshold,where the target geographical location is a geographical locationconfigured in the application;

a time difference between a moment of executing a to-do list and acurrent moment is less than a first preset time threshold; and

a pre-trigger condition of an operation habit event, where a momentmeeting the pre-trigger condition is earlier than a moment meeting anoccurrence condition of the operation habit event.

In a possible case, the pre-trigger condition of the operation habitevent includes any one or more of the following:

a time difference between a moment at which the operation habit eventoccurs and a current moment is less than a second preset time threshold;and

a distance between a current geographical location of the terminal and alocation at which the operation habit event occurs is less than a secondpreset distance threshold.

In a possible case, the authentication unit includes:

a first authentication subunit, configured to: if it is detected thatthe application initiates the PPG authentication request, performmatching between the most recently collected PPG signal and a stored PPGtemplate signal, to complete PPG authentication.

In a possible case, the apparatus may further include:

the detection unit is configured to: before the first authenticationsubunit performs matching between the most recently collected PPG signaland the stored PPG template signal, detect whether a time length betweena moment at which the PPG signal is collected most recently and acurrent moment is less than a preset time length.

Correspondingly, the first authentication subunit is specificallyconfigured to: if the time length between the moment at which the PPGsignal is collected most recently and the current moment is less thanthe preset time length, perform matching between the most recentlycollected PPG signal and the stored PPG template signal.

Further, the apparatus may further include:

a re-collection unit, configured to: if the time length between themoment at which the PPG signal is collected most recently and thecurrent moment is greater than the preset time length, collect a currentPPG signal of the user.

The first authentication subunit is specifically configured to performmatching between the PPG signal currently collected by the re-collectionunit and the PPG template signal, to complete PPG authentication.

In a possible case, the apparatus may further include:

a pre-authentication unit, configured to: after the collection unitcollects the current PPG signal of the user, perform matching betweenthe collected PPG signal and a stored PPG template signal, and store amatching result as a PPG authentication result.

The authentication unit includes:

a second authentication subunit, configured to: if it is detected thatthe application initiates the PPG authentication request, invoke a mostrecently stored PPG authentication result.

In a possible case, the apparatus may further include:

a time validity detection unit, configured to: before the collectionunit collects the current PPG signal of the user, detect whether a PPGauthentication success result of most recent successful authenticationmeets time validity, where that the PPG authentication success resultmeets the time validity indicates that a time length between a moment ofgenerating the PPG authentication success result and a current moment isless than a preset valid time length.

The collection unit is specifically configured to: if the time validitydetection unit determines that the PPG authentication success resultdoes not meet the time validity, collect a current PPG signal of theuser.

The embodiments in this application are all described in a progressivemanner. For same or similar parts in the embodiments, refer to theseembodiments, and each embodiment focuses on a difference from otherembodiments. The apparatus disclosed in the embodiments is describedrelatively simply because it corresponds to the method disclosed in theembodiments, and for parts related to those of the method, refer to thedescription of the method.

A person skilled in the art may be further aware that, in combinationwith the examples described in the embodiments disclosed in thisspecification, units and algorithm steps may be implemented byelectronic hardware, computer software, or a combination thereof. Toclearly describe the interchangeability between the hardware and thesoftware, the foregoing has generally described compositions and stepsof each example according to functions. Whether the functions areperformed by hardware or software depends on particular applications anddesign constraint conditions of the technical solutions. A personskilled in the art may use different methods to implement the describedfunctions for each particular application, but it should not beconsidered that the implementation goes beyond the scope of thisapplication.

The steps in the method or algorithm described in the embodimentsdisclosed in this specification may be implemented directly by hardware,a software module executed by a processor, or a combination of hardwareand a software module. The software module may reside in a random accessmemory (RAM), a memory, a read-only memory (ROM), an electricallyprogrammable ROM, an electrically erasable programmable ROM, a register,a hard disk, a removable disk, a CD-ROM, or any other form of storagemedium known in the art.

The embodiments disclosed above are described to enable a person skilledin the art to implement or use this application. Various modificationsmade to the embodiments are obvious to a person skilled in the art, andgeneral principles defined herein may also be implemented in otherembodiments without departing from the spirit or scope of thisapplication. Therefore, this application is not limited to theseembodiments described herein, but shall be construed in the widest scopeconsistent with the principles and novel features disclosed herein.

What is claimed is:
 1. A wearable device, comprising: a memoryconfigured to store software programs; a sensor configured to collect aphotoplethysmogram (PPG) signal of a user; and at least one processorcoupled to the memory and the sensor, wherein the at least one processoris configured to implement the software programs to cause the wearabledevice to: collect and store a first PPG signal of the user whendetermining the user wears the wearable device and a PPG signalpre-collection trigger condition is met; detect a first PPGauthentication request initiated by a first application in the wearabledevice; and perform, authentication by utilizing the first PPG signalstored at the wearable device without collecting a new PPG signal whendetermining a time interval between collecting the first PPG signal anddetecting the first PPG authentication request is less than a first timethreshold or when the wearable device is not taken off during the timeinterval, and perform authentication by collecting and matching the newPPG signal with a stored PPG template signal when the time interval isgreater than or equal to the first time threshold or when the wearabledevice is taken off during the time interval.
 2. The wearable device ofclaim 1, wherein the at least one processor is further configured toimplement the software programs to cause the wearable device to:implement a check-in service of the first application, implement atransfer service of the first application, implement a payment serviceof the first application, or display a first user interface of the firstapplication when the authentication succeeds; and avoid implementing thecheck-in service, the transfer service, the payment service of the firstapplication, or avoid displaying the first user interface of the firstapplication when the authentication fails.
 3. The wearable device ofclaim 2, wherein the PPG signal pre-collection trigger condition is metwhen the first application is started.
 4. The wearable device of claim2, wherein the PPG signal pre-collection trigger condition is met whenthe first application is started and a distance between a currentgeographical location of the wearable device and a target geographicallocation is less than a first preset distance threshold, and wherein thetarget geographical location is configured for the first application. 5.The wearable device of claim 2, wherein the PPG signal pre-collectiontrigger condition is met when a time interval between a moment at whichan operation habit event occurs and a current moment is less than afirst preset time threshold.
 6. The wearable device of claim 2, whereinthe PPG signal pre-collection trigger condition is met when a distancebetween a current geographical location of the wearable device and ageographical location at which an operation habit event occurs is lessthan a second preset distance threshold.
 7. The wearable device of claim6, wherein the at least one processor is further configured to implementthe software programs to cause the wearable device to: collect a secondPPG signal of the user when the user wears the wearable device and thePPG signal pre-collection trigger condition is met; and performauthentication by utilizing the first PPG signal without collecting thenew PPG signal when the first PPG signal is collected after collectingthe second PPG signal.
 8. The wearable device of claim 2, wherein afterdetecting the first PPG authentication request, the at least oneprocessor is further configured to implement the software programs tocause the wearable device to perform authentication by matching thefirst PPG signal with the stored PPG template signal without collectingthe new PPG signal.
 9. The wearable device of claim 2, wherein the atleast one processor is further configured to implement the softwareprograms to cause the wearable device to: match the first PPG signalwith the stored PPG template signal before detecting the first PPGauthentication request; and perform authentication by utilizing a resultof matching the first PPG signal with the stored PPG template signalwithout collecting the new PPG signal.
 10. The wearable device of claim2, wherein the at least one processor is further configured to implementthe software programs to cause the wearable device to: collect a secondPPG signal of the user when the user wears the wearable device and thePPG signal pre-collection trigger condition is met; and performauthentication by utilizing the first PPG signal without collecting thenew PPG signal when the first PPG signal is collected after collectingthe second PPG signal.
 11. A system on chip of a user device,comprising: a memory configured to store software programs; and at leastone processor coupled to the memory, wherein the software programs causethe at least one processor to be configured to: receive a first PPGsignal of a user of the user device when determining the user wears awearable device coupled to the user device and a PPG signalpre-collection trigger condition is met, wherein the first PPG signal isstored at the user device or the wearable device; detect a first PPGauthentication request initiated by a first application; and perform,authentication by utilizing the first PPG signal without collecting anew PPG signal when determining a time interval between collecting thefirst PPG signal and detecting the first PPG authentication request isless than a first time threshold or when the wearable device is nottaken off during the interval, and perform authentication by receivingand matching the new PPG signal with a stored PPG template signal whenthe time interval is greater than or equal to the first time thresholdor when the wearable device is taken off during the time interval. 12.The system on chip of claim 11, wherein the software programs furthercause the at least one processor to be configured to: implement acheck-in service of the first application, implement a transfer serviceof the first application, implement a payment service of the firstapplication, or display a first user interface of the first applicationwhen the authentication succeeds; and avoid implementing the check-inservice, the transfer service, the payment service of the firstapplication, or avoid displaying the first user interface of the firstapplication when the authentication fails.
 13. The system on chip ofclaim 12, wherein after detecting the first PPG authentication request,the software programs further cause the at least one processor to beconfigured to perform authentication by matching the first PPG signalwith the stored PPG template signal without collecting the new PPGsignal.
 14. The system on chip of claim 12, wherein the softwareprograms further cause the at least one processor to be configured to:match the first PPG signal with the stored PPG template signal beforedetecting the first PPG authentication request; and performauthentication by utilizing a result of matching the first PPG signalwith the stored PPG template signal without collecting the new PPGsignal.
 15. The system on chip of claim 12, wherein the softwareprograms further cause the at least one processor to be configured to:receive a collected second PPG signal of the user when the user wearsthe wearable device and the PPG signal pre-collection trigger conditionis met; and perform authentication by utilizing the first PPG signalwithout collecting the new PPG signal when the first PPG signal iscollected after collecting the second PPG signal.
 16. The system on chipof claim 11, wherein the PPG signal pre-collection trigger condition ismet when the first application is started or a distance between acurrent geographical location of the wearable device and a targetgeographical location is less than a first preset distance threshold,and wherein the target geographical location is configured for the firstapplication.
 17. The system on chip of claim 11, wherein the PPG signalpre-collection trigger condition is met when a time interval between amoment at which an operation habit event occurs and a current moment isless than a first preset time threshold.
 18. The system on chip of claim11, wherein the PPG signal pre-collection trigger condition is met whena distance between a current geographical location of the wearabledevice and a geographical location at which an operation habit eventoccurs is less than a second preset distance threshold.
 19. The systemon chip of claim 18, wherein the software programs further cause the atleast one processor to be configured to: receive a collected second PPGsignal of the user when the user wears the wearable device and the PPGsignal pre-collection trigger condition is met; and performauthentication by utilizing the first PPG signal without collecting thenew PPG signal when the first PPG signal is collected after collectingthe second PPG signal.
 20. A method implemented by a user operateddevice, wherein the method comprises: collecting a first PPG signal of auser of the user operated device when determining the user wears theuser operated device or a wearable device coupled to the user operateddevice and a PPG signal pre-collection trigger condition is met, whereinthe first PPG signal is stored at the user operated device or thewearable device; detecting a first PPG authentication request initiatedby a first application; and performing authentication by utilizing thefirst PPG signal without collecting a new PPG signal when determining atime interval between collecting the first PPG signal and detecting thefirst PPG authentication request is less than a first time threshold orwhen the user operated device or the wearable device is not taken offduring the time interval, and performing authentication by collectingand matching the new PPG signal with a stored PPG template signal whenthe time interval is greater than or equal to the first time thresholdor when the user operated device or the wearable device is taken offduring the time interval.